Variable volume pump

ABSTRACT

A PUMPING SYSTEM FOR A PLURALITY OF RECIRCULATING TOILETS SHARING A COMMON TANK IS DESCRIBED. A VARIABLE VOLUME PUMP HAS A BY-PASS VALVE WHICH IS CONTROLLED BY A PRESSURE SENSOR IN THE FLUSH LINE, TO PREVENT EXCESSIVE FLUID PRESSURE IN THE TOILETS.   D R A W I N G

United States Patent 1 1 11 1 3,833,316 Kemper 1451 Sept. 3, 1974 VARIABLE VOLUME PUMP 2.042.141: 0/1953 Grisc 417/310 x .3 7 [75] In entor: James M. Ke p Holly ood. 409.964 10/1946 Smith l74/l2 R Calif. [73] Assignee: Monogram Irrdustries,lnc., Los Primary w L Fresh Angelesi Cahf- Assistant Examiner-Richard Sher v [22] Filed; Jan. 17, 1972 Attorney, Agent, or Firm-Leonard Golove et al.

[2!] App]. No.1 218,288

Related US. Application Data [62] Division of Ser. No. 16,740, March 5. 1970. [57] ABSTRACT [52] us. c1 417/307, i84/6.4. 184/14 A Pumping System for 11 plurality of recirculating 511 1111. c1. F04b 49/08 leis Shuriiig ii Common tank is described A variable [58] Field 01 Search .1 417/307, 310. 313; vvlumc pump has 11 y-p valve which is controlled 134/64 4 39 3 7 2 by :1 pressure sensor in the flush line, to prevent exces- 220/85 3 sivc fluid pressure in the toilets.

[ References Cited 1 Claim, 1 Drawing Figure UNITED STATES PATENTS 3.021.790 2/1962 Brunsun 1. 4i7/3H) X VARIABLE VOLUME PUMP This is a division of application Ser. No. 16,740, filed Mar. 5, 1970.

This invention relates to circulating fluid systems and, more particularly to an improved variable volume pump.

In self-contained, recirculating sanitation systems, of the type currently in use on large aircraft, and, to some extent on trains and other vehicles, it has been the practice to use a plurality of substantially independent, recirculating toilet systems, each with its own filter and pump assembly and storage tank.

Typical self-contained recirculating toilet systems have been shown, for example in the U.S. Pat. to J. W. Deitz, et al., No. 3.067,433, or in the U.S. Pats. to N. J. Palmer, Nos. 3,458,049 and 3,473,171, among others. An improved system which provided a common tank and filter connected to a pair of independent toilets, each with its own pump has been disclosed in the U.S. Pat. to Corliss, No. 3,079,612.

As the size of aircraft and other vehicles increase to accomodate greater numbers of passengers for journeys of substantial duration, sanitation facilities must be provided in sufficient numbers to serve the expected usage. However, an important consideration for the proprietor of the aircraft or vehicle, is the timerequired to perform maintenance on the sanitation system, and the time required for vehicle turn around, during which the sanitation system must be serviced, and when necessary, drained and recharged with fresh fluid.

With systems of the prior art, the provision ofindividual tanks for each toile't unit is less than satisfactory because of the servicing time required, The system described by Corliss, represents a substantial improvement in that only a single tank need be drained and recharged for each pair of toilets. Yet other problems arise in systems employing a plurality of toilet units, each with its own pump. If, for any reason, a pump becomes disabled, then its toilet is inoperable and out of service, thereby limiting the facilities available for use. Because space on a vehicle is at a premium, it is uneconomical to provide extra facilities and any failure is likely to result in substantial passenger inconvenience.

Further, the additional usage imposed upon the remaining toilets may, in fact, accelerate any incipient failures which would then compound the problem. It is also to be noted that the task of maintaining toilet systems is not the most desirable one, and it has been deemed preferable to limit, wherever possible, the number of elements requiring repair, service, or maintenance. Other systems have been suggested in which a single, high volume pump is connected to serve several toilet units all of which share a common storage tank. Each toilet has a 3-way valve which by-passes unwanted flush water back to the waste tank when the toilet is not being flushed. ln order to flush a particular toilet, the 3-way valve is operated to divert flush water into the bowl instead of the drain line. Such a system has several disadvantages. For example, with this system, the pump filter is operating at full capacity at all times whether one or all toilets are being flushed, contents of storage tank are continually being agitated, and

solids are kept flowing toward the filter, increasing the likelihood of filter clogging.

ln accordance with the present invention, it has been discovered that an oversize, high volume pump can be modified to serve a plurality of toilet units. In a preferred embodiment of the invention, a high volume pump is provided with an internal by-pass relief valve, that returns fluid from the outlet side to the inlet side of the pump thus by-passing the output line. The relief valve is controlled by a pressure sensor connected to the output line. When a toilet flush valve is actuated, the pump is energized and the pressure sensor ascertains the fluid pressure in the line.

If the fluid pressure exceeds a preset limit, the relief valve is operated to divert fluid flow from the output line, thereby reducing the pressure in the output line.

The novel features which are believed to be characteristic of the invention, both as to organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing in which several. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only and is not intended as a definition of the limits of the inventron.

The FIGURE is a side sectional view of a variable volume pump according to the present invention.

FIG. 1 is a side sectional view of a variable volume pump 10 according to the present invention, and suitable for use in the systems described below. The pump 10 includes a motor 12 which is fastened to a top cover plate 14. A motor drive shaft 16 passes through the plate 14 and is coupled, by a connector member 18, to a pump drive shaft 20.

The pump drive shaft 20 includes a drive gear 22 which meshes with a transmission assembly 24, to rotationally drive a filter basket 26. The pump drive shaft 20 terminates in a pump impeller 28 which draws fluid from the pump interior and drives the fluid through an outlet duct 30. A check valve 32 in the duct 30 permits unidirectional flow offluid from the pump to an output line 34, which is coupled to the several utilization devices (not shown). A small by-pass orifice (not shown) is provided adjacent to the check yalve 32 to facilitate self-draining of the output lines and to preclude freezing of the lines in low temperatures.

The filter basket 26 is rotatably attached to a pump bottom plate 36, which includes a pump inlet orifice 38, by fastening means, here shown as a bolt 40. The filter basket 26 itself has a ring gear 42, integral with the inner periphery of the basket 26 at its upper, open end. A filter basket drive gear 44 is driven from the gear train of the transmission assembly 24.

The filter basket 26 includes a plurality of parallel circumferential slots 46 which serve to filter the fluid taken into the pump 10. A plurality of scraper blades 48 is carried by a suitable shaft 50. The blades 48 protrude through the slots 46 to dislodge any solid matter as the basket 26 rotates.

Thus far, the pump 10 is generally similar to pumps of the prior art which have been employed in similar systems. The pump 10, in addition, includes a by-pass valve 52 which is controlled by the pressure in the output line 34. The by-pass valve assembly 52 includes a valve stem 54 which carries a valve head 56 that seats against a by-pass opening 58 in the pump outlet 30. When opened, the by-pass valve 52 permits fluid to flow through the by-pass opening 58 to a return line 60 which is opened to the interior of the filter basket 26.

The by-pass valve stem 54 extends through a fluid impermeable diaphragm member 62. In a separate, vented chamber 64, the valve stem 54 is biased into the closed position by a spring member 66, resting upon a spring plate 68. In the valve chamber 70, which is separated from the sealed chamber 64 by the diaphragm 62, a fluid inlet 72 is provided which couples to a pressure sensing line 74. I

By appropriate selection of the dimensions of the pressure sensing line 74, or of the coupling member which connects the pressure sensing line 74 to the main output line 34, the operating region of the by-pass valve 52 can be determined. When the pressure in the output line 34 rises above a predetermined setting, approximately PSI, the fluid pressure in the valve chamber 70 exceeds the bias spring pressure and the valve stem 54 is moved to the right as viewed in FIG. 1, opening the valve.

Fluid then by-passes-the output line 34 and returns to the inlet side of the pump through the interior of filter basket 26 through the by-pass return 60. The low impedance return path reduces the pressure in the output line 34. Since a substantially closed feedback loop is involved, the pressure in the output line 34 will stabilize at the preset magnitude. If more than one utilization device is on-line," the pressure in the output line 34 will drop. A reduction of pressure enables the bias spring 66 to move the valve stem 54 to the left, closing the by-pass valve 52 and increasing the pressure in the output line 34.

As an additional feature of the pump 10, a differential pressure equalizer assembly 80 is provided to protect the transmission assembly 24 and a gear box 82 in which it is located. Normally, the gear box 82 and the housing 84 in which the pump drive shaft is located. are charged with a lubricant 86. Shaft seals are of course provided to prevent fluids from entering the gear box 82 and to prevent lubricant 86 from leaking out of the gear box 82. Since a primary cause of leakage would be a pressure differential, as between the interior of the gear box 82 and the environment in which it is located, the pressure equalization assembly 80 is provided. An elastic, fluid tight bag member or envelope 88 is fastened to the exterior of the gear box 82 and is in fluid communication therewith through a duct 90.

While the lubricant 86 normally stays within the gear box 82, any lubricant that might escape is retained within the interior of the envelope 88. Any changes in pressure either cause the envelope 88 to expand or contract, thereby providing a variable volume which can be affected by pressure changes. Any leakage of lubricant 86 is retained in the envelope 88. Subsequent pressure changes permit the lubricant to be returned to the gear box 82.

However, other arrangements consistent with the present invention can be devised by mechanics skilled in the art without the exercise of additional invention.

What is claimed as new is:

1. For use in a fluid distributing system including a utilization device and a fluid reservoir, a variable volume pump comprising in combination:

a. pumping means having an inlet and an outlet and including a motor, a pump, transmission means coupling said motor to said pump, and pressure equalizing means coupled to said transmission means for preventing leakage of fluid between said transmission means and a reservoir resulting from pressure differential therebetween;

said pressure equalizing means including a flexible fluid-tight sac in fluid communications with said transmission means, adapted to be located in the reservoir, whereby pressure differentials as between the reservoir and said transmission means result in fluid flow between said sac interior and said transmission means while maintaining fluid isolation as between said transmission means and the reservoir; and

a filter interposed between a fluid supply and said inlet;

b. fluid delivery means connecting said pumping means outlet to the utilization device;

c. fluid pressure sensing means connected to said fluid delivery means and adapted to provide first signals representing the pressure of fluid being supplied at the utilization device; and

d. by-pass means. connecting said pumping means outlet and inlet and being coupled to said fluid pressure sensing means, said by-pass means being connected to apply fluid from the outlet side of said pumping means to the inlet side of said pumping means, between said filter and said inlet. said bypass means being operable in response to applied first signals for diverting sufficient fluid from said pumping means outlet to said inlet to maintain the fluid pressure at the utilization device at a desired 

